Oscillating sander



May 30, 1944- A. G. DECKER 2,350,098

OSCILLATING SANDER Filed Dec. 31, 1941 '7 Sheets-Sheet 1 May 30, 1944. A. G. DECKER OSCILLATING SANDER Filed Dec. 3l. 1941 '7 Sheets-Sheet 2 May 30, 1944.

A. G. DECKER OSCILLATING SANDER Filed Dec. 3l, 1941 7 Sheets-Sheet 3 May 30, 1944. A. G. DECKER OSCILLATING SANDER '7 Sheets-Shea?l 4 Filed Dec. 3l, 1941 06)@ C@ C) @D @'51 May 30, 1944 A. G. DECKER l 2,350,098

OSC ILLATING SANDER mn ess I l @3M May 30, 1944 A. G. DECKER OSCILLATING SANDER Filed Dec. 31, 1941 '7 Sheets-Sheet 6 IIIINH m Cllonzg Dec/fer May 30, 1944. A. G. DECKER OSCILLATING SANDER '7 Sheets-Sheet 7 Filed Dec. 31, 1941 amm- Alonzo @pee/tem .Patented May 302.1944.

SCILLATIN G SANDER Alonzo G. Decker, Baltimore, Md., assigner to The B lack and Decker Manufacturing Company, a corporation of Maryland Application Decemherl, 1941, Serial No. 425,181

(Cl. 51-170) l l 11 Claims.

The invention relates to a reciprocating sander head per se and as a feature of a manually supported and directed power driven tool, more parl ticularly, an electric tool though other power sources may be employed.

In operation the sanding member or pad is reciprocated on an extremely short approximately rectilinear path which may be either transverse to a radius of thehead or in the direction of such radius, according to the various forms of the invention to be disclosed and the said transverse motion may be either on an arc,

. so short as to be approximately rectilinear or it may be a true rectilinear motion defined by slide guides. It is regarded as an important accomplishmentthat the pad element may support a small piece of sand paper or emery cloth or other abrasive surface, giving the effect of an abrasive sheet pressed by two ngers against the parts which are being sanded and moved back and forth by oscillation of the fingers. To this extent the operation of the machine simulates the hand l sanding operation, making it possible for the pad to enterinto and operate within 'corners or other small crevices and confined areas and in grooves or channels'formed by machining and similar operations. whereby suchinternal surfaces and concavities can .be treated. v

.movesV at a rate of from, three to four thousand strokes per minute performing many times the work which can be performed by hand.v The strokesmay be from one half inch to one inch in length averaging less than half the! radius of the gear casing.

It is also regarded as of importance thatthe oscillating sander of the invention is provided with a palm engaging grip above the center of oscillation and the casing is adapted for enclosure in the hand, so that the tool can be operated, supported and directed in and by one hand. It is also of importance that the pad is spaced outward radially from beneath the grip so that the Work is in full view and not obscured by the grip or casing.v i l While various forms of power operated Sanders are available they are found insuilicient for this purpose in that theydo not enterv and are not adapted to operate in conned areas as described and the work and the pad are partly concealed from the operator during the'sanding operation so that hand work is necessary.

The fact that in the various forms of the invention to be described, the sander head is angularly adjustable about the axis from which the arm carrying thepad radiates, such adjustment being adapted to the positioning o! the arm at any angle substantially throughout the arc of 360 is regarded as an important contribution to the resultI attained in that the path of the sanding member or pad may be transferred or adjusted to any desired angular relation to the l grip.

'Ihe various forms of reciprocating sander head illustrated are adapted to the accomplishment of the result described and other sanding operations generally performed by hand, Vthus giving a wide increase in the amount of work performed vby the workman in a unit of time without sacrificing the quality of the product, certain forms being preferred on account of increased emciency or simplicity and commercial advantage.

While the sander head may be otherwise supported and driven, it maybe noted that in the preferred form shown the drive shaft or rotary driving member which operates the oscillating sander arm is mounted in the grip to which the sanderhead is attached, the shaft bein'g` driven by .ha motor or other driving source having its While a hand operation is simulated' the pad axis transverse to and preferably at right angles Y to said drive shaft. In the form shown the motor is enclosed in a barrel like casing to the end of `which said ball grip is secured.` While other typesof grip and casing are usable, the ball like grip and barrelr casing are preferred, for enclosure in the hand, this arrangement being of important advantage in holding and directing the sanding head in and by onev hand of the op- .erator with the pad spaced outwardly from beneath the grip so that the work and pad .are

always visible at the ends of the ilngers of the operator. f Y

In the accompanying drawings, I have illustrated a preferred and various modified forms o f the apparatus adapted to the accomplishment of the object of. the invention.

In the drawings;

Fig. 1 is aside elevation of a manually supported electric tool drawn to scale and equipped with a sander head according to the invention, the said sander head and adjacent parts being broken away andshown in section on a vertical plane of the tool axis.

Fig. 2 is a fragmentary view of the head and the ball like gear casing, the same being in the nature of a bottom plan of the sander head of Fig. 1, but on an enlarged scale, the barrel being broken away. y

Fig. 2a is a section on line 2cv-2a, Fig. 1.

Fig. 3'is a view similar to Fig. 1 but showing a secondV form of head in which the sanding inem-h ber reciprocates on a short and hence nearly straight arc,

Fig. 4 is a fragmentary bottom plan view of the sander head of Fig. 3 showing the grip end or gear casing, the barrel being broken away,

Fig. 5 is a horizontal section looking downwardly from the line 6 6 in Fig. 3,

Fig. 6 is a view similar to Fig. 1 showing la modified form of the construction Figs. 3, 4 and 5,

Fig. 7 is a fragmentary view in the nature of a bottom plan of the oscillating sander head Fig. 6, the barrel like casing being broken away rearwardly of the head,

Fig. 7a is a section on line 'Ia-1a, Fig. 6,

Fig. 8 is a vertical section on the line 8-6 in I Fig. 6 looking in the direction of the arrows,

Fig. 9 is a view similar to Fig. 1 show'ing a modified form of oscillating sander head of the type of Fig. 1 in which the sanding member is guided to reciprocate on a guided rectilinear path,

Fig. 10 is a Afragmentary view in the nature of a bottom plan showing the oscillating sander head of Fig. 9, the barrel being broken away rearwardly of the head,

Fig. 10a is a fragmentary section on li'ne Illa-Ilia, Fig. 9.

Fig. 11 is a view similar to Fig. 1, showing an oscillating sander head in which the pad moves on a straight line, radially disposed as to the drive shaft and grip,

Fig. 12 is a fragmentary view in the nature of a bottom plan of the sander head, Fig. 1l, the barrel being broken away rearwardly of the head,

Fig. 12a is a section on line I2a-I2a, Fig. 11,

Fig. 13 is a view similar to Fig. 1 showing an oscillating sander head in and by which the radial and transverse paths are combined,

Fig. 14 is a-fragmentary view in the nature of a bottom plan view of the oscillating sander head of Fig. 13, the barrel being broken away rearwardly of the same,

Fig. 15 is a section looking upwardly from the plane indicated by the line I5-I5 in Fig. 13,

Fig. 16 is a diagrammatic view illustrating the path of the center of the pad and the center line of the arm which carries the pad,

, Fig. 17 is a front end view of the construction in Fig. 1, showing ball-like grip as in the other I v"forms illustrated, and

l Figs. 18 and 19 are detail views showing modified forms of pad and attachment for the pad and abrasive sheets.

Referring tothe drawings by numerals each of which is used to indicate the same or similar parts in the different figures and having particular reference to Figs. 1 and 2, the construction shown comprises a reciprocating sander head indicated in a general way by reference character I. While other operating means may be employed within the broad conception of the invention, this sander head, as shown, is operatively mounted on a manually supported and directed electric tool unit 2, particularly adapted to this purpose. This unit has a barrel or similar field casing 3, containing an electric motor not shownysuch a motor would have its axis coincident with the axis of said casing, which, as shown, includes at its rear end a brush housing or the like 3' which is shown as coaxial and continuous with the field casing proper.

Gear casing 4, as shown, projects forwardly from the barrel and is ball-like or semi-spherical as to its forward upper portion 5 and rearwardly thereof it is of approximately circular outline about a horizontal axis at 5' where it is attached to the field casing. The ball-like portion is to be seated in the palm of the hand. the lower end of the casing being shown as of downwardly reducing taper forming a finger grip or seat terminating at 6".

Gear casing 4 contains a normally upright rotary member or shaft 6 for driving the sander head, the same being mounted in suitable antifriction bearings 'I and 8 in the upper and lower l areas of the gear casing 4, said shaft being driven by a bevel gear 9 mounted thereon and meshing with a pinion I6 on the motor shaft.

Regarding the term, upright, it is assumed, for convenience, that the normal position of the tool is that which it would take in working on a horizontal upwardly exposed surface. 'I'his assumption is resorted to at times throughout the application.

The drive shaft 6 is preferably at right angles or at a. convenient angle to the motor shaft and to the axis of casing 3, such relation being referred to as transverse. The oscillating sander head may, however, be otherwise supported and driven.

In the form shown the gear casing 4 is formed with a gear chamber II, preferably concentric with the axis of the shaft 6 and ofy suflicient diameter to admit the gear 9, the said chamber II being also preferably open to the right into the field casing 3 through the threaded shank I2 whereby the gear casing, in the form shown, is secured to the field casing 3.

The chamber II is shown as formed with a bottom opening I4, the term bottom having relation to what may be termed the normal attitude of the tool as above described. The opening I4 is shown as internally threaded to receive a plug I5 which is suitably bored at 6 to receive the bearing 8 which may be forced up against shoulder I6 in any suitable manner as by means of screw plugs I'I and I8 screwed upwardly against the lower bearing 6.

An important feature of the plug I5 is that it is provided with a peripheral bearing surface I9, which, in the form shown, encircles a dependingy ring 26, the ring 20 and the surface I9 being to the best advantage concentric with the drive shaft 6 and preferably terminating above in a downwardly disposed circular flat surface 2l approximately transverse to the shaft 6, the details of construction being subject to such variation as would be obvious to a designer of such machines.

The reciprocating sander head, in the form shown, which is subject to variation as suggested, comprises a casing or frame formed in upper and lower sections 22 and 24 which may have horizontal contacting surfaces 25 and 26. This casing or frame contains a central chamber 21. A laterally or horizontally oscillating arm 28 is mounted on a pivot pin 29 intermediate of said armx being supported above and below by said casing sections 22 and 24. The chamber 21 in said casing is of dimensions sufficient to permit free oscillation of said arm about the pin 23 as herein after described. The sections 24 and 22 of the casing are fastened together by screws 56. The outline of the pad and the preferred form of casing sections 24 and 22 are shown in plan in Fig. 2.

In the form shown, the shaft 6 is provided at its lower end with a depending 'eccentric or crank pin 30 encircled by a. bearing ring or follower 3| which operates in a slot 32 in an end of arm 2l extending in the direction of Y the length of said arm. In the form shown,

ward end with a slot 34 similar to the s1ot32,.

i. e., longitudinally disposed in arm 28. This slot is engaged by an operating pin 35 rigidly connected to follower member 39 and shown as projecting upwardly therefrom, and follower member 33 has a shank 31 which may be of suitable cross section and which slides in a slot 38 in the bottom member 24 of the sander head casing.- This slot is shown as rectilinear and at right angles to the length of the arm 28 in mid-position. Shank 31, according to the illustration, extends downwardly from follower 33 which overhangs the shank 31 and has rectilinear elongated sides 40 adapted to ride in and be guided by a guide-way 4I in the bottom member 24 approximately at right angles to the length of the arm 28 in mid-position in which it extends forwardly from shaft 6. 4I is shown as at the upper side of the slot 38 and of increased width as compared to said slot and extending downwardly from the top surface 26 of the casing section 24. The co-operation of approximately rectilinear follower surfaces 40 with way 4I prevents turning of the pad member 42 about its axis, and said member is caused to reciprocate on a path which is approximately a straight line by oscillating arm 2l being operated after the manner of a hand sanding method herein identified.

It is of considerable importance that the sanding head casing, particularly its upper section 22, is provided with a curved approximately circular surface 43 which, as shown, is an internal or inwardly disposed surface adapted to enclose the ring 20 with its external circular surface I3, said surfacesbeing in engagement, and, as shown, the sanding yhead I preferably has an upwardly disposed circular flat surface peripherally arranged and indicated by reference character 44 which engages the downwardly disposed surface 2l on the gear casing and particularly in this instance formed on the plug l5. It may also be noted that, in the form shown, the head casing, particularly the upper section 22 thereof, includes an upwardly disposed ring member 45 having the inner peripheral surface 43 and the top flat surface 44 formed thereon and that this ring member is split radially and cut away formr ing a slot 46, Fig. 2, to permit of tightening or clamping as by means of a tangential screw 41. In the form shown, this screw projects into a peripheral groove 48 inA the depending ring 20. This arrangement provides for the turning of the reciprocating sander head I to any position of adjustment through an arc of 360 about the drive shaft E and provides for clamping said head in any of the various positions of adjustment thus provided whereby the path of the sanding pad member 42 to be described may be shifted in its angular relation to casing 3, 4, to a series of positions relative to said casing.

In the form shown, the follower, including shank 31 and top portion 39, are made in a single piece with the follower pin 35 extending upwardly therethrough provided with splines 23, pin 35 is secured in any suitable manner in shank 31 as by forcing into place.

The pad member 42 as shown has a hub 41' Guideway shown in section vand provided with a horizontal flange at 48' to support the pad. This hub member is apertured and 4splined at 23' to receive the pin 35 and the lower projecting end of the pin 35 is threaded at 49. The yielding material 5| and flexible plate 50 are secured to flanges 48' by screws 46 threaded upwardly. An abrasive sheet 52 is secured by means of a nut 53 engaging the thread 49. This nut also secures the entire pad member 42 to shank 31 to which it is thus removably attached. Pads usable with the machine are to be more fully hereinafter described.

' While the details of construction have been fully described in order 'that the disclosure may teach the construction of an apparatus in accordance with the invention, it will be understood that these details are capable of wide variation.

The operation of this sander will be apparent from the description. The head being assembled as described and shown, the motor in the casing 3 being energized, the pad 42 with the abrasive sheet 52 thereon, is reciprocated with a short approximately rectilinear motion and at a high speed from three to four thousand strokes per minute being feasible. This operation, except for the speed attained, is closely similar to hand sanding. While the results attained are equal to those attained by hand sanding, the rate of accomplishment is widely multiplied.

It is also important that the sanding head, i. e., the casing 22, 24, with the parts therein, including the sanding pad member and follower `and the oscillating arm. and the path of the pad may be adjusted about the driving shaft 5 and about the axis of` gear casing 4 through an arc of 360 and secured in Various positions of adjustment at any angle to casing 3, 4. It is also notable that the short stroke, and approximately rectilinear motion make it feasible to operate in confined areas as small grooves and channels and various crevices and corners which have previously been treated by hand and regarded as not accessible to and with the regular power sanding apparatus.

It is of interest that the ball-like gear casing 4 is adapted to fit in the palm of the hand,

the fingers extending down to or toward ring 20. The barrel 3 is also of small diameter shown as about 21A, the ball shaped casing `4 being of similar diameter and having its axis at right angles to that of the barrel.

In operating the member 4, being seated in the palm with the -fore finger and second finger extending downwardly toward ring 20, the barrel being grasped by the remaining fingers and thumb the tool is in very satisfactory one hand control with the pad spaced outwardly from beneath the grip and immediately below theeds of the fingers so that thek control of the pad is very similar to that attained in the hand operation with the speed many times multiplied.

Referring now to Figs. 3, 4 and 5, it will be nfted that this illustration includes the field or motor casing 3. gear casing 4 and the motor 60 in said casing and a cooling fan 6I, all of which are elements of the construction Fig. l, the motor and fan not being indicated therein.

The oscillating sander head 63. in this insance. is connected to and operated from the motor but in a manner to be distinguished from the operation of the construction Fig, 1, the result attained being similai with relation to hand sanding. l

The sanding head 63 like that shown and described in connection with Fig. 1 comprises upper and lower casing members' 64 and 65, the latter being, however, more in the nature of a plate attached by screws 65.

In this instance, the sander head comprises an oscillating arm 466 which is pivotally mounted in the casing 64, 66, as by means of a pivot pin I1, has its upper end extending upwardly into the upper casing member 64 and seated therein. The arm 66 is-supported by the plate 65, the pivot pin being at the rear end of arm 66 remote from the pad member 15.

The upper casing member 64, see Fig, 5, is preferably chambered as shown at 68 to admit and enclose the arm 66 and to provide for its oscillation about the pin 61. Tothis end, i. e. that it may be thus oscillated the arm 66 is slotted longitudinally at 69 and this slot is engaged by a follower block which ts and slides in the slot 69. Block 10, as shown, is formed with a central internal or female bearing 1l. This bearing 1| is engaged by an eccentric pin or crank pin 12 extending downwardly from the drive shaft 6 which may be mounted and driven in the manner disclosed in connection with Fig. 1 providing for oscillation of arm 66.

It may be noted asof advantage that the slot 69 in the arm 66 preferably does not extend down through the arm and it thus serves to support the follower block 10 on the bottom 69 of the slot and that the bottom face of the upper member 64 of the casing may be chambered at 64' to permit the block to project upwardly thereinto, and the block 10 is preferably elongated relatively to its stroke so as to bridge the eccentric chamber 12 at all times and prevent displacement of the block.

'I'he arm 66, as illustrated, extends forwardly from pin 61 in an approximately diametrical direction across the base of casing 4, in accordance with the preferred form, protruding from and beyond the casing 64, 65 and gear casing 4 and being provided at its outer end with a sanding pad member 15 to which abrasive material 16, prefer.. ably in the form of an abrasive sheet as emery cloth or sand paper is secured in a suitable manner to be described. This pad is preferably of small dimension so that it carries an abrasive sheet of a size 'and in a manner, form and arrangement and attains an eil'ect similar to the effect obtained in and by rubbing the work with such abrasive sheet pressed against the work by the lingers of one hand.

It is of advantage that the end of the arm 66 carrying the abrasive, i. e., the sanding pad, projects outwardly from the casing so that the pad and the work can be seen from all sides by the operator and in the preferred arrangement the abrasive is supported below the bottom plate 65 of the casing as most clearly observed in Fig. 3,. Thus the operation of the abrasive is free of obstruction and in full view of the operator.

It is also noted that the oscillating sander head 63 is adjstable about the axis of the drive shaft 6 to give a variety of angular adjustment and location of the path of the pad relatively to the gear casing 4 and the motor or field casing v3. An adjustment range of 360 is obtainable and may be regarded as preferred. As a, clamping means for holding the sander head `63 in any desired position of adjustment, the clamping screw 16 may be arranged transversely of the radial slot 11 in the sander head casing as shown in Fig. 4 and previously described. The upper portion of the latter casing section 64, indicated at 18, is preferably in the form of a ring' surrounding and enclosing a depending ring 19 on the gear casing or more particularly on the bearing plug 88 therein. The ring 18 may be split at 11 as described and clamped by means of screw 16 or other clamping means may be provided. The adjustment disclosed is capable of variation being similar to that in Figs. 1 and 2. The other details disclosed are likewise subject to changes of design.

This form of sander head is regarded as particularly eillcient in its performance of the equivalent of hand or nger sanding operation, particularly, in conned areas as grooves, corners and the like, where up to the present time only hand work has been regarded as feasible.

The sanding pad, Figs. 3, 4, and 5, may to advantage be like that shown in detail and described in Figs. 6, 7 and 8 being clamped in position by the screw 80' and held against displacement by the transverse shoulder 8|, see Figs. 3 and 5. The pads shown are to a considerable extent interchangeable.

Referring now to Figs. 6, 7 and 8, it will benoted that these figures show the details of a pad which is regarded as satisfactory for various machines of this general type. vThese figures also show a sanding head of similar operation but of somewhat different construction as compared to that shown in Figs. 3, 4 and 5. l

Figs. 6, 7 and 8 show a motor or eld casing 3 and a gear casing 4, arranged as previously described, the motor as shown in Fig. 3, having its axis coincident with the axis of the cylindrical casing 3. While this arrangement is preferred, the oscillating sander head may be otherwise driven and supported.

In the form shown in these figures, the sander head casing of the construction previously described is replaced by an upper guide and supporting plate or frame 83 which has an upwardly projecting horizontal ring or bearing portion 84. I'he ring may be split at 85 as shown in Fig. 7, or provided with any suitable clamping features. In the split form shown the ring is contracted in clamping by means of a screw 86 transverse to said split. The ring 84 with its clamping screw 86 are related to an inner ring 81 preferably of the form disclosed in connection with the previous ilgures, and in the manner described. In other words, thisv sanding head in the preferred form is angularly adjustable in what has been herein termed a horizontal plane about the axis of the driving shaft ,6, the adjustment being most conveniently provided to operate through an angle of 360, though it is believed that a lesser angular adjustment would generally be sufficient. Certain features of novelty in this and other forms of the invention disclosed are, however, to be treated as independent of the angular adjustment of the head.

'I'he head shown in these figures comprises a sanding pad member 83 to be further described, the same being seated in the outer end of an oscillating arm 89 which is pivotally mounted on the plate 83 being preferably on the bottom 0f said plate permitting the pad to be mounted directly on the arm 89 and at the same time placing the abrasive surface ofthe pad well below the arm and frame. Also the arm is free for dismounting to permit removal of abrasive and metal dust and the like which may accumulate in and about the bearing surfaces and for other purposes. As shown, this arm, in its mid-position,

is diametrically related to the rings 84 and 81 but spaced downwardly below said rings or adjustment bearings and gear case 4.

The arm 89, in the form shown, is pivotally mounted on a pin or other bearing 90 on one side of the center of the shaft 6, said bearing being, in the form shown, formed on a screw 9| threaded upwardly into the plate 83 and having suitably engageable head 9|' for operation of the screw. The head 9|' takes over and supports the arm, it being understood that any suitable bearing 90 from which the arm may be conveniently removed may be employed. The arm 89 is further guided and supported on a bearing pin 92 at the opposite sidel of the axis of rings 84, 81, and gear casing 4 from said journal 90. Said pin journal 92 may be supported on a screw 92' or otherwise and it has a head 93 or other suitable means for supporting the arm 89 from beneath. The pin journal 92 engages a slot 94 in `the arm for the purposes stated, said slot being approximately transverse to a radius about journal 90 and to said arm. Between journal 90 and 9| the arm 89, as shown, is also slotted at 95 in the direction of its length, this slot 95 isoperatively engaged by a block 96 which flts and slides in said slot. This block, as shown, has straight sides 91 spaced according to the width of the slot and parallel to each other, and this block is, in turn, engaged by an eccentric or crank pin 98 projecting downwardly from the shaft 6 into a journal bearing 99 in the block.

plate |05. The pad member is intended to be used with an abrasive sheet |01. In operation the abrasive sheets naturally become worn out or exhausted from time to time and must be replaced. When the worn sheet is removed or in initially applying an abrasive sheet, the new sheet is passed horizontally across the bottom of the pad and the end edges |08 are drawn up over the ends of the pad |02 and plate |05, which are duly assembled, and said edges are seated in the rabbets |08, the base or frame |05 and pad |02 having been removed from the upper member, support, or arm 89, and retained in assembled relation for this purpose. In seating the end edges |08 of the abrasive sheet |01' in the rabbets or apertures |06, these end edges are punctured by the pins |03 and passed down over the same. The assembled pad member is then pressed upwardly against the arm or support 89, the projecting ends of the pins |03 being inserted in the holes -|04. Then the screw |09 which supports the pad member 88 on the arm 89 is threaded into the hole ||0 Vprovided in the base or plate |05 for this purpose and duly tightened, securing the pad member to the arm and tightly securing the abrasive sheet |01 to the pad |02 in connection with which it is accurately positioned and held against displacement by the pins |03 in the holes |04. The pad member is further positioned relative to the arm 89 by the shoulder which forms the end wall of a seat ||2 formed in the arm 89 for this purpose.

The block 96, as shown in Fig. 7, is circular in plan, the surfaces 91 being chords of said circle, which leaves arcuate top flanges |00 at each side projecting laterally from the slot 95 over the top of and engaging the top surface of the arm 89 yon each side of said slot. These flanges |00 serve to support the block 96. In the construction shown the bottom surface of .the plate 83 is chambered at |0| to admit the flanges |00 and the top portion of the block 96 which projects upwardly into said chamber. It will be apparent that all the operating parts are supported by screws 9| and 92', avoiding the necessity for a bottom cover plate or the equivalent, as in Fig. 3.

By the operation of the shaft 6 and eccentric pin 98 and sliding block 96 andthe guiding and supporting journals 90 and 92, the latter operating in transverse slot 94 as described, the center of the pad 88 is given a reciprocating motion in a direction approximately at right angles to the radius from the center of shaft 6 which in the particular arrangement shown, is approximately twice the throw'of the eccentric 98 and approximately half the radius of gear casing 4. The sanding pad member 88, shown in connection with the tool in Figs. 6, 7 and 8, though particularly adapted to this machine and those of Figs. 3, 4, and 5, and Figs. 11 and 12 is capable of more general application. It consists of a pad` proper |02 provided with four or any suitable number of upwardly projecting pins |03 which t in corresponding holes |04 which may be formed in the end of the arm @s or other suitable support. The pad member 88, as shown, has a frame or supporting plate |05 through which the pinsextend via holes |04' and from which'they project into holes |04 of arm 89 or other support, the pins and holes being essentially arranged lin proper relation.

In the form shown the base plate or frame |05 of the pad member is slotted or rabbeted at |06 or otherwise a suitable aperture is provided between arm 89 or other upper support and the 75 By this arrangement of the pad relatively to the arm 89 the pad projects outwardly from beneath the gear casing and the sander head casing or frame and also downwardly well below the moving parts of the machine as well as below the stationary frame or plate and by eliminating the bottom cover plate from the casing a degree of obstruction is removed from the vicinity oi. the pad and the latter thus advanced beyond the moving and the stationary members of the head is more easily and universally applicable to the work and the degree of visibility of the work and u of the pad'in operation is greatly increased by the elimination of obstructions existing in other machines for this purpose.

As already pointed out, this sander head is particularly adapted to the performance of sanding operations in grooves and corners'and other conned areas and elsewhere under circumstances in which sheets of abrasive material have previously been applied by the pressure of one or more ngers of the hand which ilngers are moved with a reciprocating or rubbing motion.

In the drawings, Figs. 6 and 7 are approximately full size, Fig. 8 being an enlarged view. 'I'he drawing therein discloses gear casing 4 and barrel 3 as of dimensions to be easily grasped in the ngers of one hand, as in Figs. 1 and 3 In the form Figs. 3 and 6 the path of the pad though arcuate is approximately rectilinear being an exceedingly short arc, which, in the form shown, is approximately a sixth of the length of the oscillating arm and a small fraction of the radius of the gear casing. These proportions are for illustration and are subject to variation, the short stroke being preferred.

The ball-like gear casing 4 rits in the palm of the hand with the ngers extending downwardly over the nose a4 to the ring 84 whereby the pad member 88 is placed just forwardly of the iingers which gives a guiding and controlling relation of The construction is conveniently supported and directed in and by one hand.

' Figs. 9 and 10 show a motor casing \||0. and

a gear casing I I-I. These though subject to wide variation are, in the lform shown, formed and related in the manner already described. These figures show an oscillating sanding head, indicated in a general way by reference character ||2. This head, in the form shown, is connected to the gear casing I|| for angular adjustment about the axis of the drive shaft 6 in the manner already describedor in any suitable manner. In other words, the parts already discussed, ex-

cept the details of head I I2, may be substantially the sanding head frames and casings alreadydescribed. 'I'his frame or casing |I4 as shown is provided at its inner end, beneath the gear casing with an upright ring or bearing member I5, which, as aforesaid, engages a depending ring or journal I| on the gear casing and is adjustable about the axis of the shaft 8. It is secured in any position of adjustment in any suitable manner as by a tangential screw I I6 arranged transversely of a radial split in said ring I|5 as at |I6', other methods of adjustment and clamping being regarded as ieasible.

In the form shown, which is for purposes of illustration, the details being largely selective, ,the shaft 8 projects downwardly from the center of gear casing III through the frame or supporting plate ||4 by way of aperture II3, provided for this purpose, and the shaft 6 has extending downwardly Irom its lower end an eccentric pin or crank pin I I1 which engages longitudinal slot I I8 in the inner end of oscillating arm I I9. While pin III is shown as engaged directly with slot I|8, any suitable bearing may be employed. The arm IIB operates a sanding pad member |20 at its outer end to be further described. This arm IIS is plvoted on the frame or plate II4 intermediately of the length of said arm between said eccentric or crank pin I|1 or its slot II8 and the outer end of said arm where the said pad member |20 is mounted or supported. This pivot is shown in the form of a journal |2| supported on said plate or frame ||4 and extending downwardly therefrom. This journal I2I is shown as located closely adjacent the eccentric slot II8, so that the outer end of the arm I I9 which operates the pad member |20 has a throw or path the length of which is several times the throw of the eccentric II'I, the latter being extremely slight as indicated in the drawings, Figs. 9 and 10, which are full size, according to the machines as so far constructed.

The oscillating arm ||9, in the form shown, is formed at its outer radial or swinging end with longitudinal slot |24 engaged by a pin |25 projecting upwardly from the pad member |20. It may be noted that the arm IIS extends outward radially from beneath the gear casing III, its mid position being at the center line of plate ||4.

In the form of the invention shown in Figs. 9 and 10, the pad member |20 or more particularly the follower |21, which is connected to said member and carries the Dad, is mounted to relciprocate its path being substantially rectilinear and transverse to the length of the arm in midposition.

To this end guide members |25 are secured to the plate or frame |I4 beneath the same or in what may be referred to as a depending relation thereto.

These-guide members |25 form a guideway |28' extendingin the direction of motion, already described, i. e., transverse to the length of oscillating arm ||8. This guide way in the form shown is of what may be described as a T shaped cross section, i. e., said guide members |28 are oilset or grooved at |28 forming a widened portion of the way at the top. The widened portion of. the way at |28 is covered by relatively thin plates |29 and |20' spaced apart as shown to provide a path for pin |25.

'I'he guide members |28 and the cover plates |28, |29 as shown are spaced downwardly from the frame or supporting plate ||4 by two elongated blocks |30 at each end parallel to the arm I|9. The guide members |25 and said blocks |30 and cover plates |29, in the form shown, are held in position by four bolts I3I. 'I'hese extend upwardly from suitable seats in the ends of the guide members I 26 and through the blocks |30, plates |29 and the plate or frame member ||4 which is of suillcient width for this purpose, see Fig. 10.

It may also be noted that, in the form shown, the bolts I3| engage slots |32 in the plate ||4. These slots are of considerable length and are approximately parallel to the arm IIS in midposition. These slots, incidentally, are of a length corresponding to the length of the slot |24 in the arm ||8 and thus provide for the adjustment of the position of the ways |26 in a radial direction toward or from the shaft 5A whereby the position of the pad member |20, and particularly its drive pin |25 and hence the path of pin |25 and pad member |20 about the shaft 6 may be changed to suit the'operator. In this way the operator can vary the length of the path of reciprocation oi the pad member |20 to meet the changes of conditions involved in and by the change of work.

In the form of the invention shown, the upper enlarged area or flange |36 of follower |21 which its in the offset and widened portion of the ways at |28 and serves to support the pad member |20 and follower |21 is formed with parallel rectilinear way engaging surfaces |31. Below the follower |21 is the hub |38 of the pad member |20. The hub |38 is in operation secured to follower |21 by threading on to the middle threaded portion |39 of pin |25. The extreme lower end of pin |25 is in the form of a depending screw |39' of reduced diameter as compared to said middle portion |39. 'I'he screw |39' is `adapted to be engaged by hat nut |44. The

lower end of said hub I 38 is ilanged at |40 and the pad |42 is supported from above by ilexible plates |4| and a center ring |50 which is attached to flange |40 as by means of screws |43 threaded through said plates and said ring portion of the pad and upwardly into ange |40.

The nut |44 enters a suitable depression in said pad and serves to secure an abrasive sheet |5I and likewise to secure the pad member v|20 and its hub |38 to the follower |21.

While the pad shown at |42 is circular in form, other types of pad can be operated by this oscillating sander head, important features of which are the convenient adjustment as to the length of the stroke, the projection of the pad member well down below the operating mechanism sothat it is free of obstruction, and the ability to use a highly flexible pad, the pad member |42 being exible for a large portion of its radial length and approximately half its area. Other features of importance are the extreme simplicity of construction and consequently low cost and the ability to perform what has been regarded as essenbelow all other moving and stationary portions of the machine, thus avoiding obstruction of the area around the pad and.giving a relatively unobstructed view of the work and the pad and particularly th'e area of the work near the pad. This head has the advantage of a straight line path of adjustable length and the advantage of one hand support and direction from the end of the fingers as previously described. The rectangular pads may be used with this sanding head.

Referring now to Figs. 11 and 12, it will be noted that in the form illustrated the motor casing or field casing |54 and the gear casing |52 are as i1- lustrated in the gures previously described and this arrangement has important advantages in the way of the convenience with which the oscillating or reciprocatng pad is directed and supported by one hand of the operator, however, other forms of casing and drive are usable and the various features of the oscillating sander head of these and other figures are regarded as capable of more general application.

In the construction illustrated in Figs. 11 and 12, there is an oscillating sanding head indicated in a general way by reference character |55. This head comprises an upper member or casing |56 and a bottom cover plate |51. While this particular form of casing has advantages in connection with the operation to be described, particu.. larly, in guiding and supporting the oscillating arm and in the exclusion of grit and the like from the contacting sliding surfaces of said arm |58 and the guideway to be described, it is subject to some variation in the light of previous disclosures in this application, other methods of supporting and driving the reciprocating or oscillating arm being contemplated.

It may be noted that the top member of the casing |56 is shown as provided with an upwardly projecting horizontal ring |59 which encloses a corresponding ring or journal member |60 de pending from the gear casing |52 so that the journal member |60 is adapted for adjustment in a normally horizontal plane and about the axis of shaft 6. The ring |58 is shown as split at |6|, said split being closed by a screw |62. This or any suitable means may be employed for adjusting and clamping the casing |56, |51 in any desired position of angular adjustment about the gear casing |52 and/or motor casing |54 whereby the path of the sander pad to be described is shifted about saidl casing |52|54 or other hand grip.

An important object of the construction Figs. 11 and 12 is to provide a sander of the general type described in which the pad is reciprocated on a path which is in approximately radial relation to the drive shaft 6 and/or the gear casing |52 or other hand grip said path being disposed in the general direction of the length of the arm |08 and spaced downwardly beneath the hand grip and preferably adjacent the finger tips for which a suitable frustoconical seat is provided at |62' in the various forms shown, the term downward is used for convenience as having relation to the posion in which the tool is shown.

In view of the various constructions herein shown, it is feasible to provide oscillating sanding heads, having respectively the oscillating and approximately straight, or a true straight line or rectilinear path said strokes or path being radial as in Figs. 1l and 12 or tangential, i. e., at right angles to a radius as in Figs. 9 and 10 and other similar figures all of said heads being operable by and from a single portable tool unit as indicated at |52 and |54, and adjustable relatively to the same to operate at any angle to and with the gear casing or other hand grip or casing. Ii' desired, several different heads may be adapted for use with a single grip and/or tool unit.

Referring again to the details of Figs. 11 and 12g it will be noted that the upper casing member |55 is formed with a guideway |62, the center line of which is radially related or approximately so related to the drive shaft 6 of the head and to the casing or grip |52, however, a degree of displacement of this center line from this exact locat lon would not seem material except insofar as it might be sufficient to interfere with the eilicient operation of the arm |58 from and by said shaft or any equivalent device and its control and direction from said grip in the manner described.

In the form shown the arm |58 has rectilinear side surfaces |63 and the way |62 has corresponding inwardly disposed rectilinear surfaces |64 disposed in the general direction of a diametrical center line, indicated for convenience at |65. Said direction or path being preferably capable of change and/or adjustment in the manner described.

The reciprocating or oscillating arm |58, in the form shown, is supported and held in said ways by the bottom plate |51 which is secured in the form illustrated by means of screws |66, being guided by sliding contact of surfaces |63 and |64.

In the form shown, the arm |58 is provided at its outer end with an abrasive pad |61 positioned by a flat transverse shoulder |68 on said arm and secured in any suitable manner as by means of one or more screws |69, a suitable form of pad being shown in Figs. 6 and 8. Fig. 12 shows in broken lines a second position of adjustment of said pad and arm and path which is merely an example of the effect of the adjustments described, also shown in Fig. 7.

The arm |58 is reciprocated in said ways in relation to said head and said gear casing |52 in the form of the invention shown, by an eccentric or crank pin |10. This pin |10, in the form shown, has a rotary engagement with a disc or bushing |1| shown as eceentrically bored to receive said pin and seated in the center of a rectangular slide block |12 tting in sliding relation in transverse way |13 which may be formed in the arm |58. In the form shown the Way |1| extends downwardly into said arm being closed at the bottom at |14. Also in the form shown, the top section of the casing |56 is chambered above the path of the bearing block or slide block |12, said chamber being indicated at |15 and tending to provide freedom of motion of theblock |12 and bushing |1| in the operation indicated, avoiding unnecessary friction of the block with said casing section. The details are described for completeness of disclosure and subject to tion. Y

In performing the sanding operation in crevices and confined areas and particularly in grooves and ways and the like, it is in many instances desirable to operate the pad in a radial direction giving a relation of the abrasive sheet to the work closely similar to that attained in the hand operation previously found necessary under such circumstances. The sanding head shownn Figs. 11 and 12 is adapted to perform such sanding operations at high speed increasing the output and the economy of production in and by a considerablev percentage.

It is also to be noted that the reciprocating or oscillating motion described in connection with the reciprocating sanding heads herein disclosed in various forms is more like the hand sanding operation both in the type of motion and in the results attained than is therotary sanding operation most generally practiced in power sanding. Itis also noted that the machine herein described maintains, more nearly than has previously been possible, the condition of clear observation of the pad and the work and direct ilnger direction and control of the pad. The rotary sanders require special attention, and skill on the part of the operator on account of the tendency to score and groove the work whereas the reciprocating type of sanders herein described eliminate almost completely the tendency to score and give relatively high speed with results in and to the work similar to those attained by hand operation. 'I'he term reciprocating as herein applied has reference to' a backward and forward motion substantially on a single approximately rectilinear path.

Figs. 13, 14, and 16 illustrate a sander head in which the motion of the pad may have both a tangential and a preferably slight radial comvarialated to shaft Sand gear casing or palm grip |19. In the form shown, the shaft 8 is provided with a depending eccentric or crank pin |9| shown as extending downwardly from the lower end of said shaft and forced into-a ring |92. This ring forms the inner race of a roller or other suitable bearing |93. The outer race of the bearing, in the form shown, is in the nature of a suitable inwardly disposed circular surface |94 which may be formed in the arm |88 or a suitable outer race may be inserted therein. The

ponent as illustrated diagrammatically in Fig. 16, the point X the locus or path of which is shown being a point on the pad preferably the center of the pad member |11 and of the operating or driving pin |18 therefor.

The construction shown in these figures includes a gear casing |19 and a tleld casing |80' as previously described. While this arrangement has important advantages in connection with the type of sander disclosed, as already pointed out. the various combinations of parts described in connection with the sander head are capable of more general application.

The sander head |82 as shown comprises a cassections |84 and |85 preferably having a suitable ring or other adjustable connection |86 to the gear casing |19 whereby the head may be tuinei'l about the axis of the drive shaft 6 and/or gripI casing |19 and clamped in any suitable angular relation thereto as by means of a clamping screw |81 or other clamping means which may span a slot in the ring |86 or operate according to any suitable clamping method.

In the form shown, as in the other forms already described, there is an oscillating arm |88 which may be said to reciprocate with a slight deviation from a single rectilinear path. As shown, there is a pivot pin |89 suitably supported in the casing in parallelism with the shaft 6. This pin or journal |89, as shown, engages a slot |90 in the end of the arm opposite to the pad member |11 said slot being preferably elongated in the direction of the length ofV said arm which is an approximately radial direction as rebearing |98 and the adjacent portion of arm |88 is thus given a circular motion about the axis of shaft 6. The details' being illustrative and subject to variation.

The outer radial end of the arm |88 is engaged by the previously mentioned padoperating pin |18 which extends upwardly therethrough being integral with the shank of sanding pad member |11, the pad |11' thereof, in the form shown, is of rectangular shape, elongated transversely to the length of the arm |88 and to the corresponding radius of shaft 6 though this precise form and size are unimportant except that all the pads used with the machines disclosed are preferably of the small size indicated, providing for the use of a small motor to drive them which motor is suitable to the one hand control unit ldisclosed, the pads likewise being suitable to the operation described.

In operation the pad has a motion which varies slightly from actual reciprocation on a single path being advanced and returned onslightly different lines so that the abrasive particles assisted by a slight motion of the machine as a whole are continually displaced from any single path which displacement is of advantage in that the tendency to scoring or grooving, which has been found diicult to avoid in the prior art power driven sandng apparatus, is completely eliminated.

The slot |98 in Fig. 13 is of suiilcient area to permit free movement of the pad on and along the path described. This slot is in lower casing section |85.

This motion closely simulates the highly desirable but relatively slow hand operation and is suitable not only to the treatment of at surfaces and uniformly curved surfaces but is particularly adapted to operation in crevices and confined areas as grooves and the like which it has reviously been found necessary to surface by and.

The disclosure Figs. 13 to 16 demonstrates that the invention may not in all forms be closely confined to the reciprocation of the pad precisely on a' single rectilinear path.

Figs. 18 and 19 show forms of pad and pad supports particularly adapted for use with the construction Figs. l, 9 and 13. Fig. 18, for example, shows the shank 200 depending from the follower member as per Fig. 1, externally threaded at 20| to engage a lock nut 203 and internally threaded at 204 to receive a flat headed screw 205. The pad proper 206 is apertured at the center to pass over the screw threaded shank 200.

In assembling-the pad on the shank 200, the nut 203 is first turned up slightly above the position shown in the drawings, a washer 201 is then passed up over the shank into contact with the nut, the pad 206 is then engaged with the shank and passed upwardly against the washer and the screw 205 is inserted and turned upwardly to a position shown to support the pad, the head of '2,350,0984 abrasive sheet :as is Ithen-v 'placed in position to` cover the bottom of the pad and the ends of the sheet at 209 are turned upwardly over the ends of the pad and over the top of the pad, after which the washer 201 having been previously raised to admit the ends 209 of the abrasive sheet is forced downwardly against said pad by turning nut 203 downwardly whereby said ends 209 are clamped and the abrasive sheet is secured in position and is thus made lready .for any of the sanding operations mentioned, the pad likewise being suitably clamped.

It may be noted that Fig. 18 is a longitudinal central section, the pad being preferably of elongated rectangular form as shown in plan in Fig. 2, which is likewise true of the pad Fig. 19.

In the construction Fig. 19 the depending shank 2l0 of the follower is made of reduced cross section and preferably solid being externally threaded as shown. In this construction the pad 206 is mounted on a sleeve 2| I which is part of the pad member and is externally and also internally threaded and preferably flanged at its lower end at 2l! to support the pad. This sleeve carries threaded thereon abovethe pad, a lock nut or -pressure nut 203 and a washer 201, as described above in connection with Fig. 18, and beneath the washer there may be a flexible plate 2H directly overlying the pad and providing a flexible backing therefor. The pads, in all instances, may be of felt or rubber or sponge or the like.

In this instance the abrasive sheet 2 I 5 is placed in registration with the bottom surface of the pad completely covering'the same as in the previous instance, i. e., in Fig. 18, and the ends 2I6 of the sheetl are passed upwardly overl the ends of the pad and then folded over the top of the same between the top surface of the pad and said plate 2H. To clamp the ends of the pad to hold the latter in operative position, the nut 203 is screwed down against the washer 201 and thus applies pressure to the plate 2 I4 clamping the ends of the abrasive sheet in position and holding the latter in its operative relation to the pad. If desired, the flexible plate or sheet 2| 4 may be omitted, the washer 201, in most instances, being of a diameter approximately equal to the transverse dimension of the pad so that it is sufiicient to hold the ends of the sheet when pressed down by the nut 203.

The operation of the various sanding heads and pad members and the manner of directing and supporting the same has been fully described in connection with the description of each form of head and pad. While the term oscillating has been applied to the operation of certain heads particularly where the pad carrying arm swings about a center, it is noted that the `path of the :pad is so short relatively to the radius about said center as to be approximately straight so that all the heads may be said to move the pad back and forth on an approximately straight path or to cause/ it to reciprocate the slight variation from a rectilinear path being regarded as insumcient to constitute a `departure from the true definition of this term.

I have thus described the invention in several diierent forms, the description being specic and in detail in order that the manner of constructing, applying, operating and using the invention may be fully understood, however, the specific terms herein are used descriptively rather than in a limiting sense, the scope of the invention be-v ing dened in the claims.

` y What I claim as new andA desire .to secure by Letters Patent is:

1. A hand supported and directed sanding machine having a casing comprising a barrel and a ball like gearcasing with gear means therein, the gear casing being adapted vto fit in the palm of the hand and serving as a hand grip whereby the tool is supported in and directed by one hand of the operator, a sanding head having a frame and a rotary driving member, the latter being I transverse to the axis of said barrel and driven by gearing in said gear casing, an arm guided for reciprocaticn in said frame and extending outward radially beyond said gear casing and meansconnecting said arm to said rotary mem'- ber to impart a reciprocating motion to the arm,

and means for supporting a sanding pad memy ber on said arm at a` point spaced outward radially beyond and also below said gear casing, said machine having a finger end engaging surface below the-palm engaging portion and immediately above said arm.

2. A hand supported and hand directed sanding machine having a casing comprising a barrel and a ball-like grip at the end of said barrel, and adapted to fit in the palm of the hand, and having a depending nger tip engaging nose, the barrelbeing of a diameter similar to that of the grip whereby the tool is supported and directed in one hand of the operator, a sanding head having aframe and rotary driving member, the latter having its axis transverse to the axis of said barrel and an arm guided for reciprocation in said frame and extending outward radially beyond said gear casing and means connecting said arm to said driving member to impart a reciprocating motion to the arm, and means for supporting a sanding member on said arm at a point spaced outward radially from beneath said gear casing, said frame being mounted for angular adjustment about the axis of said nose whereby said arm and the pad thereon and the path lof -the latter may be shifted about and relatively to said casing, and means for clamp- Aing said sanding head in various positions of said grip, said head including said arm being mounted for angular adjustment relatively to said grip about the axis of said rotary member approximately in a plane transverse tosaid axis, means for securing said head in various positions of adjustment whereby the path of said pad member is shifted about said grip, the path of said pad being approximately rectilinear.

4. A hand supported and directed sanding machine comprising a hand grip, a rotating driven member therein, an oscillating sanding head comprising an arm mounted to reciprocate and receiving a reciprocating motion from said rotating member, and extending outwardly beyond said grip,v said arm beingadapted to carry a sanding pad member thereon spaced outwardly from said grip, said arm being pivotally mounted at a point in its length remote from said pad member and having a longitudinal slot for en.-

`wardly from said grip and having an: eccentric gagement with said pad member and a guide transverse to the length of said arm in midposition, whereby the direction of motion of the pad is controlled.

5. A hand supported and directed sanding machine comprising a hand grip, a rotating driven member therein, an oscillating sanding head comprising an arm mounted to reciprocate and receiving its reciprocating motionl from said rotating member, and extending outwardly beyond said grip, said arm being adapted to carry a sanding pad member thereonspacedoutwardly from said grip, said arm being pivotally mounted at a point.- in its length remote from said pad member and having-a longitudinal slot for engagement-with said pad member and a'guide transverse to the length of said arm in mid posil meansfor said arm. coniining it to a predetermined path in the direction of its length, and means on said arm for supporting an abrasive `member located outward radially from and bey wardly from said grip and carrying an eccentric tion, whereby the direction of motion of the pad is controlled, and means providing for the adjustment of said guidel in they direction of the length of said arm to vary the length of the path of the pad. u

6. A hand supported and directed sanding machine comprising a casing having a ball-like palm engaging grip, the grip being adapted for inclosure in one-hand of the. operator vwhereby the tool is adapted to be supported and'directed in and by one hand of the operatonsaid balllike grip containing a rotary driving member, a sanding head having aframe, means whereby said head is supported on said ball member for angular adjustment about thesame, means `for securing said frame in various positions of adjustment about an upright axis ,throughv said grip, means supported in said frame and extending outward transversely to said axis beyond the outer periphery of said ball-like member and adapted to support a sanding member'at its vouter end, means for reciprocating the said supporting means-:and s'aid sanding memberl on a short approximately rectilinear path.

7. A hand supported and directed sanding machine comprising a ball-like palm engaging grip, the grip being adapted for inclosure in one hand of the operator whereby the tool is adapted to in said frame, an arm disposed in an approximately radial direction as to said axis and extending outwardly beyond said grip, and having a slot with a block slidably engaging said slot and having a bearing therein for said eccentric vwhich imparts a harmonic motion to said block transversely of said slot whereby said arm is given a reciprocating motion, said frame `having guiding means for said arm conning it to a predetermined path and means on said arm for supporting an abrasive member located outy ward radially from and below said grip and frame and for securing said member to said arm to Vmove therewith and, said abrasivemember having an abrasive surface spaced downwardly below said arm and said frame and disposed transversely of said shaft, vsaid slot being` arranged transversely ofsaid arm and'said guidbe supported in and by one hand, said ball-like grip containing a rotary member, a' sanding head having a frame, means whereby said head is supported on said ball member for angular Aadjustment about the axis of said rotary member and grip in directions transverse to said axis, and means for securing said frame in various positions of said adjustment, means supported and guided in said frame and extending outward radially of said ball-like member and adapted to support a, sanding padmember at its outer end, means operated by said rotary member for reciprocating the sanding member and said support on a short rectilinear path, which is approximately half the radius of said ball.

8. In a hand supported and directed sanding machine having a hand grip, an oscillating sanding head supported on said hand grip and'com'- prising a frame, a rotating shaft extending -d'ownin said frame, an arm disposed inl an.approxi,y

mately radial vdirection as to saidgaxisiandfexi tending outwardly beyond said grip, and havingja slot with a block slidably engaging-fs'aidjslot'andhaving abearing therein for said eccentric which imparts a harmonic motion to said .block trans-v versely vof said slot whereby said arm is given a reciprocating motion, said frame having guiding ing .means and path being disposed Vvin-` the direction of the length of the arm.

10. In a hand supported and directed sanding machine having a hand grip, a reciprocating sanding head supported on said hand grip and comprising a frame, a rotating shaft extending -downwardly 'from said grip and having an eccentric in vsaid frame, an arm disposed in an approximately radial direction as to said axis and extendingoutwardly beyond said grip, and having a slot with a block slidably engaging said slot and having abearing therein for said eccentric which imparts a harmonic motion to said block vtransversely of said slot whereby said arm is given a reciprocating motion, said frame having guiding means for said arm confining it to a predetermined path, and means on said arm for supporting an abrasive member located outward radially from and below said grip, said abrasive member having an abrasive surface spaced downwardly below said arm and said frame and disposed transversely of said shaft, said frame and grip having cooperating means providing for the angular Vadjustment of said frame and said path about said'shaft.

f 11. A hand supported and directed sanding machine having a hand grip consisting of a gear casing of ball-like form, and adapted to t into thepalm of a hand whereby the tool is supported and directed by one hand of the operator, reducing gears in said casing, a barrel of which vsaid casing forms the end, an electric motor in (j, said-barrel having a driving connection to said gears; a reciprocating sanding head supported voiigsaidV handgrip and vcomprising a frame, a

rotating driving member connected to and driven -by'said gears, said rotary driving member extending: dk'iwnwardly from said grip and having an i eccentric means thereon, an arm disposed in an approximately radial direction as to said axis and extending outwardly beyond said grip, and

having a slot with a block slidably engaging said slot and having a bearing therein for said eccentric which imparts a harmonic motion to said block transversely of said slot whereby said arm is given a reciprocating motion, said frame having guiding means for said arm confining it to a predetermined path and means on said arm for supporting an abrasive member located outward radially from and below said grip and for securing said member to said arm to move therewith, and, said abrasive member having an abrasive surface spaced downwardly below said arm and said frame and downwardly disposed, said guiding means confining said arm to a motion transverse to its length and said slot being disposed in the direction of the length of the arm the ma chine as thus arranged providing for the placing of the fore iinger of the operator holding the grip with his right hand immediately adjacent to the pad whereby the abrasive member is l0 directed with the maximum of precision.

ALONZG G. DECKER. 

